1. Field of the Invention
The present invention relates generally to electrical switching apparatus and, more particularly, to terminations, such as terminals, for a circuit breaker.
2. Background Information
Electrical switching apparatus include, for example, circuit switching devices and circuit interrupters such as circuit breakers, contactors, motor starters, motor controllers and other load controllers.
Low voltage circuit breakers, for example, which are used in power distribution systems, are commonly mounted, either alone or in combination with additional switchgear, within a housing (e.g., without limitation, a load center). Frequently, the load side of the circuit breaker and the terminals thereof are disposed in the back of such housing thus providing very little space for accessing the circuit breaker load terminals. This makes attaching electrical cables, for example, to the load terminals difficult. Adding to this difficulty, certain electrical regulations impose minimum wire or cable spacing and bending requirements.
Certain ANSI regulations govern what cable landing configurations and current loads are permitted at the load terminals of a circuit breaker based on the particular type of cable being used. For example, for 500 Thousand Circular Mils (MCM) copper cable with 75° C. insulation in conduit, the maximum allowable load per cable is 385 A. Accordingly, for a 400 A application, for example, it is necessary to provide two cable terminals, and three terminals are provided for an 800 A application. There is, however, one exception in the National Electrical Code which permits 500 MCM cable to be upgraded from a 385 A load rating to 400 A for loads of 800 A and below. Therefore, when specified by a customer, one cable may be used for a 400 A application and two cables for an 800 A application.
In view of the foregoing, there is a well known, longstanding difficulty in the electrical switching apparatus art with regard to being able to provide desired or required electrical connections within confined spaces. For example, because the load terminals of certain circuit breakers typically extend substantially perpendicularly from the back of the circuit breaker, any electrical cables, for example, connected to such terminals, require a minimal amount of bending space between the terminal and the back of the enclosure (e.g., load center) in which the circuit breaker is installed. In order to address these considerations, known circuit breaker devices for minimizing cable spacing include a variety of bussing assemblies.
FIG. 1 illustrates the load side 2 of a low voltage circuit breaker 4 employing a bussing assembly 6. As shown, the bussing assembly 6 includes load terminal extensions, which are commonly referred to as runbacks 8. A separate vertical adapter or riser 10 made of a conductive material (e.g., without limitation, copper) and including a plurality of holes 12, is attached to each of the runbacks 8 in order to allow several standard, one-cable terminal lugs 14 to be mounted thereto. The one-cable terminal lugs 14 are mounted at an angle (i.e., sloping either upward or downward with respect to FIG. 1) based upon the desired cable entry (i.e. top or bottom) configuration (e.g., terminal lugs 14 are mounted sloping downward for cable entry from the bottom of FIG. 1). The multiple mounting locations on the risers 10 permit a plurality of cables (not shown) to be electrically connected to each terminal and also permits the standard terminal lugs 14 to be sloped, thereby reducing the amount of cable bending, and thus space, required for the cables (not shown). However, such a design is limited by the number of standard one-cable lugs 14 that can be mounted upon the risers 10 (e.g., four lugs 14 are mounted on each riser 10 in FIG. 1). Efficiency of the design is further reduced by the limitations imposed by the aforementioned applicable electrical codes and regulations.
There is, therefore, room for improvement in the art of terminal lugs for electrical switching apparatus. There is also room for improvement in electrical switching apparatus employing such terminal lugs.